extending extract logic declarations names example to support data structures

[fernando-vs]

hi,

im trying to extend the example provide for pylang that extracts the names of logic declarations in a file so that it supports data structures defined using typedef in verilog. This is an example of the code I'm parsing:

package definitions;
    parameter VERSION = "1.1";

    typedef enum {ADD, SUB, MUL} opcodes_t;

    logic [7:0] c;
    
    typedef struct { 
        logic [31:0] x, y;
        opcodes_t opcode; 
    } instruction_t;
    
    function automatic [31:0] multiplier (input [31:0] a, b);
        // code for a custom 32-bit multiplier goes here
        return a * b; // abstract multiplier (no error detection)
    endfunction 

endpackage

Using the code of the example as it is, it is going to extract all logic declarations except for x and y:

Found 4 logic declarations:
   1. c
   2. a
   3. b
   4. multiplier

I've been working on trying to get to the instruction_t declaraction but has not been succesful. I can get the declaration using:

tree.root.members[3]

    
    typedef struct { 
        logic [31:0] x, y;
        opcodes_t opcode; 
    } instruction_t;

, and doing some exploration with:

tree.root.members[3].type.members[0].type
 
        logic [31:0]

, but i have not been able to get the rest of the data. I assume I should be using a visitor somehow for this, but the calls in the original code doesnt seem to look inside the definition of the data structure. Probably I'm missing something at the moment.

Any suggestion is more than welcome.

thanks.

[MikePopoloski]

It's not clear what you're missing. You already have the members of the struct with tree.root.members[3].type.members what is the rest of the data that you can't get?

[fernando-vs]

thanks for the response. yes, i can get the members but then i need to iterate over them and check their type to find logic variables and once i find one i need to get the variable names and bit width associated with them. that is what the data that i need. for example for the code in question:

    typedef struct { 
        logic [31:0] x, y;
        opcodes_t opcode; 
    } instruction_t;

, i need to be able to find the two logic signals x and y and get the bit with which is 32 bits. the least i need are the variable names, but i havent been able to find that data after extracting the members.

[MikePopoloski]

You got the type of the first member with tree.root.members[3].type.members[0].type. You can get the name with tree.root.members[3].type.members[0].name. You can get the other members by using indices other than zero.

[fernando-vs]

ok, name is not working for some reason:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
AttributeError: 'pyslang.pyslang.syntax.StructUnionMemberSyntax' object has no attribute 'name'

, type i can get it:

logic [31:0]

but i was expecting something in the same lines of what happens with variables that are not defined in a data structure. the type for this is IntegerTypeSyntax but for other logic variables is ScalarType. I just want to make sure I'm not going in the wrong direction, if this is as far as we could get it is fine, i just thought it would be similar for variables in a data structure but it looks like it is a bit different.

[MikePopoloski]

Oh, I thought you were looking at the AST. You're traversing the CST. You can just look at the members of StructUnionMemberSyntax to see what's in there. You want to loop over the declarators which have the individual member names.

You don't need to guess at any of this stuff. Look at members in the docs, dump with it with the --cst-json flag, debug it from Python via repr() calls, etc.